It is known to provide electromechanical systems which are reversible, such systems including, for example, storage batteries having rechargeable electrodes. In, for example, lead-acid batteries and other accumulators, it is a common practice to apply the active mass (e.g. lead-lead oxide mass) to a metal carrier which serves as a mechanical support for the active mass and as a current collector or current distributor upon discharge/charge cycling.
Because of the dependency of the life of the battery on retention of the mass on the support, considerable reseach has been carried out on techniques for improving the mechanical stability of the electrode upon charge/discharge cycling.
For example, the electrode may have one or more synthetic-resin layers which form pockets receiving the active mass. Pocketed metallic grids, wooden frame members and like systems have also been used to prevent migration of the active mass from and along the support.
The term "composite electrode" has been used by many to refer to metal/synthetic-resin electrode systems and reference may be had in this connection to the German published application (Auslegeschrift) No. 1,231,326 and U.S. Pat. No. 3,060,254 which deal with composite electrodes.
While such composite electrodes have been successful in large measure, because they do reduce the instability of the electrode structure, it cannot be entirely precluded that the active mass will, as a result of shape change during the charge/discharge cycling and especially as a result of swelling and contraction of the electrode, shed the active mass.
In prior-art systems, therefore, there is at least a partial loss of active material as a result of charge/discharge cycling.
The active material appears to deposit outside the synthetic-resin layer or to fall out of the pockets formed thereby. The synthetic-resin layers themselves are usually produced by the sintering of synthetic-resin powders or from synthetic-resin fibers.
To avoid these problems it has also been proposed to use tubular construction for the electrode, these electrodes being referred to generally as sheathed electrodes. In electrodes of the latter type, the swelling pressures, which are a consequence volume changes in the active mass, are taken up by the tubes from which the electrodes are constituted. Within the tubes there are provided metallic wires serving as current collectors of conductors. The primary difficulty with such electrodes is that they are expensive to fabricate and frequently cannot be made in an entirely reproducible manner so that all of the electrodes give the same mechanical and electrical characteristics.
As noted previously, considerable effort has been expended in developing techniques in electrode fabrication and electrode structures so that a detailed review of the art, in this connection, would be impossible to present.
However, reference may be had, in this connection, to the following nonexclusive list of patents which may be considered pertinent art:
British Pat. No. 1,018,971
U.S. Pat. No. 482,043
U.S. Pat. No. 1,051,147
U.S. Pat. No. 1,158,491
U.S. Pat. No. 2,515,204
U.S. Pat. No. 2,858,352
U.S. Pat. No. 3,560,262
U.S. Pat. No. 3,772,089
U.S. Pat. No. 3,890,160
U.S. Pat. No. 3,973,991
U.S. Pat. No. 4,048,406
U.S. Pat. No. 4,055,711
U.S. Pat. No. 4,090,897